ULTRA HIGH QUALITY RESOLUTION OF BIT MAP IMAGES
Original Publication Date: 1998-Apr-30
Included in the Prior Art Database: 2004-Apr-08
Xerox Disclosure Journal
Disclosed is a method for achieving ultra high quality resolution and conversion of bit map images. The method comprises using template matching for resolution conversion when the input and output resolution are among, for example, the following: 75, 150, 200, 240, 300, 400, 600, and 1,200 spots per inch (spi) or other divisors of 1,200. The method comprises: first resolution conversion, by identifying and converting the input binary image to 1,200 spi binary using template matching; and second image enhancement, by converting from 1,200 to the output resolution, a block of pixels at a time. In cases where the output printer is binary, there can be a subsampling and binarization step. Where the output printer has Pulse Width and Position Modulation (PWPM) capability, the 1,200 spi binary image can be converted to a lower resolution with PWPM. The algorithm employed in the method uses a priori information about the initial bit map coupled with high addressability or gray writing to achieve the improved resolution quality.